Beyond Linux® From Scratch - Version 8.2

Chapter 12. System Utilities

dbus-1.12.4

Introduction to D-Bus

D-Bus is a message bus system, a
simple way for applications to talk to one another. D-Bus supplies both a system daemon (for
events such as “new hardware device
added” or “printer queue
changed”) and a per-user-login-session daemon (for
general IPC needs among user applications). Also, the message bus
is built on top of a general one-to-one message passing framework,
which can be used by any two applications to communicate directly
(without going through the message bus daemon).

This package is known to build and work properly using an LFS-8.2
platform.

If you are still building your system in chroot or you did not
start the daemon yet, but you want to compile some packages that
require D-Bus, generate
D-Bus UUID to avoid warnings when
compiling some packages with the following command as the
root user:

dbus-uuidgen --ensure

The dbus tests cannot be run until after dbus-glib-0.110 has
been installed. They must be run as an unprivileged user from a
local session with bus address. If you want to run only the unit
tests, replace, below, --enable-tests by --enable-embedded-tests, otherwise,
D-Bus Python-1.2.6 has to be installed,
before. The tests require passing additional parameters to
configure and
exposing additional functionality in the binaries. These interfaces
are not intended to be used in a production build of D-Bus. If you would like to run the tests,
issue the following commands (for the tests, you don't need to
build the docs):

The “estimated disk space
required” reported above is obtained in a build using
the switches disabling documents generation. This and the use of
the make distclean
command implies that the build directory size is smaller than the
one for a full build with documents generated.

There has been a report that the tests may fail if running inside a
Midnight Commander shell. You may get out-of-memory error messages
when running the tests. These are normal and can be safely ignored.

Command Explanations

--disable-doxygen-docs:
This switch disables doxygen documentation build and install, if
you have doxygen installed. If
doxygen is installed, and you wish
to build them, remove this parameter.

--disable-xml-docs: This
switch disables html documentation build and install, if you have
xmlto installed. If xmlto is installed, and you wish to build
them, remove this parameter.

--disable-static: This
switch prevents installation of static versions of the libraries.

--with-console-auth-dir=/run/console/:
This parameter specifies location of the ConsoleKit auth dir.

--with-system-pid-file=/run/dbus/pid:
This parameter specifies the location of the PID file.

--with-system-socket=/run/dbus/system_bus_socket:
This parameter specifies the location of the system bus socket.

--enable-tests: Build extra
parts of the code to support all tests. Configure will end with a
NOTE warning about increased size of libraries and decreased
security.

--enable-embedded-tests: Build extra
parts of the code to support only unit tests. Configure will end
with a NOTE warning about increased size of libraries and decreased
security.

--enable-asserts: Enable
debugging code to run assertions for statements normally assumed to
be true. This prevents a warning that '--enable-tests' on its own is only
useful for profiling and might not give true results for all tests,
but adds its own NOTE that this should not be used in a production
build.

Configuring D-Bus

Config Files

Configuration Information

The configuration files listed above should probably not be
modified. If changes are required, you should create /etc/dbus-1/session-local.conf and/or
/etc/dbus-1/system-local.conf and
make any desired changes to these files.

If any packages install a D-Bus.service file outside of the
standard /usr/share/dbus-1/services
directory, that directory should be added to the local session
configuration. For instance, /usr/local/share/dbus-1/services can be added
by performing the following commands as the root user:

D-Bus Session Daemon

To automatically start dbus-daemon when the system is
rebooted, install the /etc/rc.d/init.d/dbus bootscript from the
blfs-bootscripts-20180105 package.

make install-dbus

Note that this boot script only starts the system-wide
D-Bus daemon. Each user
requiring access to D-Bus
services will also need to run a session daemon as well. There
are many methods you can use to start a session daemon using the
dbus-launch
command. Review the dbus-launch man page for
details about the available parameters and options. Here are some
suggestions and examples:

Add dbus-launch to the line
in the ~/.xinitrc file that
starts your graphical desktop environment.

If you use xdm or some other display
manager that calls the ~/.xsession file, you can add
dbus-launch
to the line in your ~/.xsession file that starts your
graphical desktop environment. The syntax would be similar
to the example in the ~/.xinitrc file.

The examples shown previously use dbus-launch to specify a
program to be run. This has the benefit (when also using
the --exit-with-session
parameter) of stopping the session daemon when the
specified program is stopped. You can also start the
session daemon in your system or personal startup scripts
by adding the following lines:

Short Descriptions

is used to start dbus-daemon from a
shell script. It would normally be called from a user's
login scripts.

dbus-monitor

is used to monitor messages going through a D-Bus message bus.

dbus-run-session

start a process as a new D-Bus session.

dbus-send

is used to send a message to a D-Bus message bus.

dbus-test-tool

is a D-Bus traffic
generator and test tool; it is a multi-purpose tool for
debugging and profiling D-Bus.

dbus-update-activation-environment

is used to update the environment used for D-Bus session services; it updates
the list of environment variables used by dbus-daemon --session
when it activates session services without using systemd.

dbus-uuidgen

is used to generate a universally unique ID.

libdbus-1.so

contains the API functions used by the D-Bus message daemon. D-Bus is first a library that
provides one-to-one communication between any two
applications; dbus-daemon is an
application that uses this library to implement a message
bus daemon.